Electron discharge device



June 26, 1945 DA|LEY 2,379,067

ELECTRON DISCHARGE DEVICE Filed April 8, 1943 ATTORNEY Patented June 26, 1945 ELECTRON DISCHARGE DEVICE Hampton J. Dailey, Bloomfield, N. J assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 8, 1943, Serial No. 482,266

4 Claims.

This invention relates to electron discharge devices, and more particularly to grid structure and mounting of the same and associated parts.

In general, the present invention is" an improv'ement upon the structure disclosed in prior Patent 2,229,050 issued January 2l, 1941, and embodies structure shown in Patent Number 2,352,208 to Knochel et al., granted June 27, 1944, and both assigned to the same assignee asthe present application.

Both manufacturing and operating difficulties have been encountered in connection with mounting and shielding control grids at their upper ends within suppressor grids heretofore employed in electron discharge devices of the character of the said prior patent. In practice a suppressor grid extends to an upper spacer and within the suppressor grid below said upper spacer is a transverse metallic shield which in turn carries an auxiliary spacer for support of the upper end of the control grid. 'Shields,

and auxiliary spacers for control grids as constructed in the past have proved unsatisfactory in use, the primary difliculty arising from difficulty of proper assembly and adequate retention of the shield and auxiliary spacer withexactitude and permanence. Delicate hand work and skilled operators were required and as a result of the difficulties encountered shrinkage in manufacture was excessiveand average production cost washigh. The present invention accordinglyis directed to overcoming the difficulties and unsatisfactory arrangements of the prior art. 1

- Generally expressed, therefore, an object of the invention is to provide an improved suppressor grid shield and assembly thereof with other parts in an electron discharge device. A

Of the same general nature, an object of'the invention is to provide a shield which may be fabricated to'precise shape before mounting in position and located definitely by virtue of its formation with respect to the suppressor grid.

Another object of the invention is to enable the shield to be readily and accurately made by punched parts and formed to seat with exactitude in the suppressor grid.

A further object of the invention is to btain-fabrication of the shield as a complete part which can be readily assembled without any distorting stresses inherent therein or introduced during fabrication.

Yet another object of the invention is to provide a shield which will also locate and fix the auxiliary insulator or spacer in proper position patents, 2,229,050 and 2,352,208.

with respect thereto and to the suppressor grid.

Still further objects of the invention will appear as the description progresses, both by direct recitation thereof and by implication from the context.

Referring to the accompanying drawing in which like numerals of reference indicate similar parts throughout the several views;

Figure 1 is an elevation of an electron discharge device embodying the present invention and shown with a part of the envelope broken away for better illustration of the structural parts therein; I

Figure" 2 is a vertical sectional View of the upper portion of the electrode assembly but with the inner electrodes in elevation;

FigureS is a sectional-plan substantially on line III-III of Fig, 2;

Figure 4 is an edge'view, substantially on line IVIV of Fig. 2, and showing a part of the suppressor grid band in section; and

Figure 5 is a perspective view of the shield before assembly in the electron'discharge device.

In the specific embodiment of the invention illustrated in said drawing, the general tube structure is in conformity with the corresponding parts shown and described in the said prior Briefly reviewed, the general assembly comprises aglass envelope l0 carried at, its lower end in a base II and having at its lower end, as a sealed part of the envelope, are-entrant stem l2 and press l3 throughwhich a part of the electrode connections are sealed. Around part of the stem is a clamp collar .14 to which are secured upwardly extending supporting rods [5. Somewhat above the press I3 is located a transverse lower insulator or spacer l6 rigidly carried by said rods which project through; edge margins of said insulator, and at the top ofsaid rods is another insulator or spacer l1 similar and parallel to'the first and also rigidly carried by said rods. The several electrodes, described hereinafter, are all between these two spacerinsulators and are directly or indirectly carried thereby.

The outermost electrode-is here shown as an anodelfl-spaced inwardly away from said rods and supported by longitudinal anode-supportingrods l9 parallel to and between pairs of the insulator supporting rods l5. The top and bottom ends of the anode are parallel to and spaced from the lower'a'nd upper said insulator spacers l6, l1 and-held rigid with respect thereto by sleeves 20 on the anode rods. Said anode rods extend above the upper insulator and-have a conductive bridge 2! connecting them and in is a suppressor grid 24 carried by posts or rods 25 within the opposite curved sides thereof and which extend through the insulator spacers l6 and I1 for support at their opposite ends. The

lower ends of these rods 25*project belowthe lower spacer and have a transverse metallic shield 26 attached thereto, said shieldgoverlying the end of the stem and press.

Next within the suppressor grid 24 is a similarly shaped but smaller screen grid 21 inparallelism ii to the anode, suppressor grid and screen grid and provided with longitudinal rods or posts3l within the curved side walls. Theserods 3| extend downwardly through the lower; insulator spacer for support and lead-in purposes, but do not extend to the upper insulator spacer. ,In-

stead, they are supported by projecting through an auxiliary insulator spacer 32 somewhat below and parallel:to the upper insulator spacer and ofsmaller size so as to havela position within the confines of the suppressorgrid 24.; Supportfor this auxiliary insulatorspacer isaccomplished, as afeature of the present. invention subsequently described herein, from the suppressor grid. Suffice it to say at the moment that this auxiliary insulator spacer also has appropriate holestherethrough for passage of the rods 28. by which the screen grid 21. is supported to enable those, rods to extend through the auxiliary insulator spacer to the upper one.

A usual or any desired type .of cathode 33 is provided within the control grid the present showing indicating said cathode to be of M .formation with the upper bights thereof-below the auxiliary insulator spacerand carried by hooksv 34 the shanks whereof extend upwardly through holes in both insulatorsthereabove and supported by springs or tensioning means 35 above theupper insulator spacer. Appropriatelead in wires 36 are provided at the bottom of. the legs of the M-shaped cathode in accordance with usualprac- 1 tice.

of the suppressor grid, the same is preferably con-v structed to have an impervious band 31 terminating the upper end of the grid body and a similar impervious band 31 terminating thelower, end of the grid body. The body of the. grid between these bands is formed as a flattened helix of wire.

Returning now to a more detailed description metallic sections or strips 38 assembled end to end with one'section 38 complementary to the other. Each section has its major portion substantially flat thereby providing an extended flat area. The end portions of each strip or section curl to a direction substantially perpendicular to the extended flat area, the curled portions of the'two sections combining to give the band semicylindrical formation at'its narrow edges.

In order to support and accurately position the auxiliary insulator spacer 32 and at the same time adequately shield the control electrode, a metallic electrostatic shield 42 is provided between the upper insulator spacer l1 and the auxiliary spacer '32. Preferably this electrostatic shield is assembled with the auxiliary spacer before those parts are assembled as a unit with the electrodes. In order to accomplish the sub-assembly of the two parts mentioned, the shield has end tabs 43 depending therefrom which pass through holes for the purpose close to the ends of the insulator spacer, said tabs being bent outwardly under the spacer after passing through the holes and then up at the outside of the spacer and inwardly at the top thereof. Except for the engagement of the tabs with the spacer, the shield is otherwise spaced away from the spacer and avoids shorting with respect to the electrodes or their supporting rods.

It is desirable, and afeature of the present invention to mount said electrostatic shield 42 accurately in position and parallel to the upper edge of the upper band of the suppressor grid. This desideratum is accomplished by providing longitudinal upstanding flanges 44 at the long edges of the shield, said flanges being parallel and spaced from each other a distance equal to the spacing of the extended fiat faces of the band 31 so as to fit nicely-within the band with the flanges juxtaposed to the contiguous parts of the flat faces of the band. The, material forming the flanges is bent outwardly and downward, as at 45, appearing in section as a hook, but as this hooked edge is coextensive with the length of the flange, it provides a long inverted trough and a long engagement with the upper edge of the band. As the bending of the flange is accomplished ,by machine with great precision, the shield will hang upon the upper edge of the band in exact parallelism to the plane of the band edge. The bent-. over or hook part of the flange may be spot welded to the band without introducing any strain or probability of causing the band to bow or bulge, this improbability being even greater by virtue of the re enforcing effect of the band by which the hook-formation is obtained. 4

The construction and assembly. of theelectrostatic shield accordingly is greatly simplified and yet it is positively positioned in very exact, parallel relation to the plane of the upper edge of the suppressor grid. It is readily slipped into place with the trough-like extended length of thebend acting as a positioning stop and re -enforcement.

.. As the flange 45 of this bent-over portionis at Each convolution of the wire forming the-grid is welded to the posts where crossing the same and the bands are likewise welded to such posts thereby forming the complete grid. Both bands are constructed identically. so a description of, one will sufiice for both.

Said band 31 is fabricated as a pair of stamped theoutside pp m n f. t e .suppressorsrid band, it is accessible for spot weldingand is consequently permanently and accurately positioned. While the invention has been describedin detail with respect to the selected embodiment presented for illustrative purposes, it isto he understood various modifications and changes may; bemade without departing from the spirit-and scope of theappended claims. I i

Iclaim: 1. A suppressor grid shield comprising a body portion of generally flat construction having opposed longitudinal side edges parallel to each other, and a flange at each said edge upstanding therefrom and formed as an inverted trough.

2. A suppressor grid shield comprising a body portion of generally fiat construction having opposed longitudinal side edges parallel to each other, a flange at each said edge upstanding therefrom and formed as an inverted trough, and means at the underside of said body portion for mounting an insulator spacer thereto and in parallelism therewith.

3. A grid structure having a part thereof formed as a band the upper edge whereof is in a plane, a shield within and transverse to said hand and parallel to said plane, said shield having flanges juxtaposed to and lengthwise of the band and said shield flanges being bent longitudinally and hooked over the said upper edge of the band locating the shield in parallelism to the plane of said edge.

4. A grid structure having a part thereof formed as a band the upper edge whereof is in a plane, a shield within and transverse to said band'and parallel to said plane, said shield having flanges juxtaposed to and lengthwise of the band and said shield flanges being bent longitudinally and hooked over the said upper edge of the band thereby rendering the flange accessible to welding electrodes both outside and inside of the band, said shield being welded by its portion of flange bent over and juxtaposed to the outside of the band.

HAMPTON J. DAILEY. 

